Module 5: The Integumentary System

Question 1

The skin makes up about ___% of body weight in the human body and covers an area of _____.

Answer 1

The skin makes up about 16% of body weight in the human body and covers an area of 1.5 - 2m².

Question 2

Integumentary system

Answer 2

The skin and its accessory structures.

Question 3

Epidermis
Dermis
Hypodermis

Answer 3

Epidermis: Outermost tissue layer of skin, composed of 4-5 layers of keratinized, stratified squamous epithelium.

Dermis: Layer of skin between epidermis and hypodermis composed mainly of connective tissue.

Hypodermis: Connective tissue connecting the skin to the underlying bone and muscle.
-Stores fat and provides insulation and cushioning.

Question 4

What are the 5 layers of the epidermis?

Answer 4

1. Stratum corneum: The outermost layer of the epidermis, replaced over approx. 4 weeks.
2. Stratum lucidum: The extra layer in “thick skin” located between the stratum corneum and stratum granulosum. It is found only on palms and soles.
3. Stratum granulosum: Grainy-looking layer of the epidermis.
4. Stratum spinosum: Spiny-looking layer of the epidermis characterised by the presence of desmosomes.
5. Stratum basale: Deepest layer of the epidermis, made of epidermal stem cells.
   - It attaches the epidermis to the basal lamina and the dermis underneath.

Question 5

Keratinocyte

Keratin

Answer 5

Keratinocyte: Cell that manufactures and stores keratin. It is the most predominant type of cell found in the epidermis.

Keratin: Type of structural protein that gives skin, hair and nails its hard, water-resistant properties.

Question 6

Dermal papilla

Answer 6

Extension of the papillary layer of the dermis that increases surface contact between the epidermis and the dermis.

Question 7

Basal cell
Merkel cell
Melanocyte

Answer 7

Basal cell: Cuboidal-shaped stem cell found in the stratum basale and in the hair matrox that continually undergoes cell division, producing the keratinocytes of the epidermis.

Merkel cell: Receptor cell in the stratum basale that responds to the sense of touch.

Melanocyte: Cell found in the stratum basale that produces the pigment melanin.

Question 8

The stratum basale is primarily made up of _____ cells but also contains ________ and ________.

Answer 8

The stratum basale is primarily made up of basal cells but also contains Merkel cells and Melanocytes.

Question 9

Which 2 parts structurally make up the skin?

Answer 9

1. Epidermis - superficial portion composed of epithelial tissue.
2. Dermis - deeper layer composed of connective tissue.
   * Hypodermis lies deep within the dermis.

Question 10

What 4 main cell types make up the epidermis?

Answer 10

1. Keratinocytes
2. Melanocytes
3. Langerhans cells
4. Merkel cells

Question 11

Desmosome

Answer 11

Structure that forms an impermeable junction between cells.

They interlock with each other to strengthen the bond between cells.

Question 12

Langerhans cell

Answer 12

Specialized dendritic cell found in the stratum spinosum that functions as a macrophage.

It engulfs bacteria, foreign particles, and damaged cells that occur in this layer.

Question 13

Keratohyalin

Answer 13

Granulated protein found in the stratum granulosum.

Question 14

Eleiden

Answer 14

Clear, protein-bound lipid found in the stratum lucidum that is derived from keratohyalin and helps to prevent water loss.

It gives keratin cells their transparent appearance and provides a barrier to water.

Question 15

There are usually _____ layers of cells in the stratum corneum.

Answer 15

There are usually 15-30 layers of cells in the stratum corneum.

Question 16

What are the 2 layers of the dermis?

Answer 16

1. Papillary layer - superficial layer made of loose, areolar connective tissue.
   - Contains fibroblasts, some adipocytes, phagocytes, and small blood vessels.
2. Reticular layer - deeper layer of the dermis made of dense, irregular connective tissue.
   - Well-vascularized with a rich sensory and sympathetic nerve supply.

Question 17

Elastin fibers

Answer 17

Fibers made of the protein elastin that increase the elasticity of the dermis, enabling movement.

Question 18

What are the 3 main pigments in the dermis that are responsible for the variety of skin colours?

Answer 18

1. Melanin
2. Carotene
3. Hemoglobin

Question 19

Melanosome

Answer 19

Intercellular vesicle that transfers melanin from melanocytes into keratinocytes of the epidermis.

Question 20

What are the 2 primary forms of melanin?

Answer 20

1. Eumelanin - black & brown shades

2. Pheomelanin - red shades

Question 21

How does exposure to UV rays cause skin to become darker?

Answer 21

It causes melanin to be manufactured and built up in keratinocytes as sun exposure stimulates keratinocytes to secrete chemicals that stimulate melanocytes.

Question 22

What are 2 advantages of increased melanin and one disadvantage?

Answer 22

Increased melanin protects the DNA of epidermal cells from UV damage and the breakdown of folic acid, but it can interfere with vitamin D production.

Question 23

Albinism

Vitiligo

Answer 23

Albinism: Genetic disorder that affects the skin, in which there is no melanin production.

Vitiligo: Skin condition in which melanocytes in certain areas lose their ability to produce melanin, possibly due to an autoimmune reaction that leads to the loss of colour in patches.

Question 24

What are the accessory structures of the skin?

Answer 24

• Hair
• Nails
• Sweat glands
• Sebaceous glands

Question 25

Hair

Answer 25

A keratinous filament growing out of the epidermis made primarily of dead, keratinized cells.

Question 26

Hair follicle Hair shaft Hair root

Answer 26

Hair follicle: cavity or sac from which hair originates. Hair shaft: part of the hair that is above the epidermis but is not anchored to the follicle. Hair root: part of hair that is below the epidermis anchored to the follicle.

Question 27

Hair bulb Hair matrix Hair papilla

Answer 27

Hair bulb: structure at the base of the hair root that surrounds the dermal papilla. Hair matrix: layer of basal cells from which a strand of hair grows. Hair papilla: mass of connective tissue, blood capillaries, and nerve endings at the base of the hair follicle.

Question 28

In hair: Medulla Cortex Cuticle

Answer 28

Medulla: the innermost layer of keratinocytes originating from the hair matrix (the hair's central core). -Not all hair has this. Cortex: the middle layer of keratinocytes originating from the hair matrix, as seen in a cross-section of the hair bulb. Cuticle: the outermost layer of keratinocytes originating from the hair matrix.

Question 29

What are the 3 parts that make up hair?

Answer 29

1. Shaft (above surface) 2. Root (penetrates dermis) 3. Follicle (2 epidermal layers surrounding the root)

Question 30

What are 4 functions of hair?

Answer 30

1. Protection 2. Sensory input 3. Thermoregulation 4. Communication

Question 31

Internal root sheath External root sheath Glassy membrane

Answer 31

Internal root sheath: Innermost layer of keratinocytes in the hair follicle that surround the hair root up to the hair shaft. -They are derived from the basal cells of the cell matrix. External root sheath: Outer layer of the hair follicle that is an extension of the epidermis, which encloses the hair root. -Base is made up of basal cells, upper regions are more keratinous. Glassy membrane: Thick, clear connective tissue layer that surrounds the base of the hair follicle, connecting it to the dermis.

Question 32

What are the 3 phases of hair growth?

Answer 32

1. Anagen phase - active phase of the hair growth cycle where cells divide rapidly at the root, pushing the hair shaft up and out. - It typically lasts around 2-7 years. 2. Catagen phase - transitional phase marking the end of the hair growth cycle. - It usually lasts around 2-3 weeks. 3. Telogen phase - resting phase of the hair growth cycle when no new growth occurs. - Lasts about 2-4 months, then another anagen phase begins.

Question 33

What are 3 things that can cause hair loss?

Answer 33

1. Hormonal changes 2. Dietary changes 3. Aging process

Question 34

Nail body Nail bed Nail root

Answer 34

Nail body: main keratinous plate that forms the nail, made up of densely-packed dead keratinocytes. -It provides protection. Nail bed: layer of epidermis upon which the nail body forms. Nail root: part of the nail that is lodged deep in the epidermis where the nail grows from, enabling the nail to keep growing.

Question 35

Nail fold Eponychium Hyponychium Lunula

Answer 35

Nail fold: fold of epithelium that overlaps the nail on each side, holding it in place. Eponychium: fold of epithelium that extends over the nail bed (aka cuticle). Hyponychium: thickened layer of stratum corneum that lies beneath the free edge of the nail. Lunula: basal part of the nail body that consists of a crescent-shaped layer of thick epithelium. Lunula

Question 36

Sudoriferous glands

Answer 36

Sweat glands, which exist to cool the body down when it gets warm. They are classified as a type of merocrine gland.

Question 37

What are the 2 types of sweat glands?

Answer 37

1. Eccrine - produces hypotonic sweat for thermoregulation via deep, coiled glands with a duct that opens on the surface of the skin. - Common on the body, especially palms, soles, forehead. 2. Apocrene - larger and deeper sweat gland that secretes thicker sweat which includes organic compounds in its makeup. - Found in armpits and genital region.

Question 38

Sebaceous gland | Sebum

Answer 38

Sebaceous gland: Type of oil gland found all over body that helps lubricate and waterproof hair and skin with sebum. Sebum: Oily substance made of a lipid mixture that lubricates skin and hair.

Question 39

What are the 3 main types of skin glands?

Answer 39

1. Sebaceous (oil) glands 2. Sudoriferous (sweat) glands •Eccrine •Apocrine 3. Ceruminous glands

Question 40

Ceruminous glands

Answer 40

Modified sudoriferous glands that produce a waxy substance (cerumen). -Found in ears.

Question 41

What are the 5 major functions of the skin?

Answer 41

1. Thermoregulation 2. Protection (from microorganisms, chemicals, dehydration, etc.) 3. Sensations (touch, pressure, vibration, heat, cold, pain, etc.) 4. Excretion and absorption 5. Synthesis of vitamin D

Question 42

Meissner corpuscle Pacinian corpuscle

Answer 42

Meissner corpuscle: receptor in the skin that responds to light touch. -Also called tactile corpuscle. Pacinian corpuscle: receptor in the skin that responds to vibration. -Also called lamellated corpuscle.